Controller for synchronous motors



[1. W. SEEGER.

CONTROLLER FOR SYNCHRONOUS MOTORS.

APPLICATION FILED FEB, 12,1921.

1 ,414,79 1 Eatented May 2, 1922;

1 z .3 L L L 1.

B M l l b 53 s1 54- 52 a r UNITED'STATES PATENT OFFICE.

EDWIN W. SEEGER, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER- HAMMER- MFG. 00., F MILWAUKEE, WISCONSIN, A CORYORATION 0F WIS- CONSIN".

CONTROLLER FOB SYNGHRONOUS MOTORS.

Specification of Letters Patent.

Patented May 2, 1922 Application filed February 12, 1921. SerialNo. 444,399.

State of \Visconsin, have invented new and useful Improvements in Controllers for Synchronous Motors, of which the following is a full, clear, concise, and exact description, reference being bad to the accompanying l0 drawing, forming a part of this specification.

This invention relates to controllers for synchronous motors.

An object of the invention is to provide a controller of the aforesaid character which 15 is adapted to automatically establish plugging connect-ions for the motor upon interruption of the running connections therefor.

Another object is to provide a controller of the aforesaid character having means re- 20 sponsive to certain electrical conditions in the field circuit of the motor for automati- V cally interrupting the plugging connections for the motor when the same approaches a condition or rest.

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates certain embodiments of the invention which will now be described, it being understood 3 that the embodiments illustrated are susceptible or various modifications without departing from the scope of the appended claims.

in the drawing,

Fig. 1 is a diagrammatic view of the controller embodying the invention;

Fig. 2 is a plan view of a mechanical interlock for certain of the switches shown in Fig. l; and

Fig. 3 is a diagrammatic View illustrating a modification of the controller shown in Fig. 1.

Referring to Fig. 1, the same illustrates a three phase synchronous motor M having a 4 stator A. to be supplied with current from a three phase A. C. circuit illustrated by lines L, L and L and a field F to be excited trom a D. C. source illustrated by a battery B.

The controller includes a five pole electromagnetic switch 1 for establishing starting connections through compensator windings 2 and 3., a three pole elect-ro-magnetic switch a for establishing running connections and a five pole electro-magnetic switch 5 for establishing plugging connections through said windings. The controller also includes an electromagnetic field control switch 6 having normally open switch arms 6 and 6 for including battery B in the field circuit of the motor and a normally closed switch arm 6 for including a discharge resistance R in said field circuit.

The control means for the aforementioned switches includes electromagnetic relays and 8, electro-magnetic dash pot relays 9 and 10 and a frequency responsive relay 11. Relay is controlled by a normally open start switch 12 and a normally closed stop switch 13 and is provided with a normally closed contact 7 and normally open contacts 7 and 7. Relay 8 is controlled by contact 7 and a normally open auxiliary switch 14: associated with starting switch 1 and is provided with a normally closed contact 8 and normally open contacts 8 and 8. Starting switch 1 is controlled by relay 9 and'contact 7 and the energizing circuit of said relay is controlled by contacts 7" and 8. Running switch 4 is controlled by contacts 7", 8 and a normallyclosed auxiliary contact 15 associated with starting switch 1 while field switch 6 is controlled by said contacts and said auxiliary switch and a normally open auxiliary contact 16 associated with runnmg switch 4:. Plugging switch 5 is controlled by contact 7. relays 10 and 11 and a normally open auxiliary switch 17 associated with said plugging switch. The energizing circuit of relay 1() is controlled by contacts 7". 8 and auxiliary switch 15 while relay 11 is arranged to be connected in the field circuit of motor'M by switch arm 6.

The operation and circuit connections of the aforedescribed controller will now be more fully set forth. Closure of start switch 12 establishes an energizing circuit for relay 7 extending from line L by conductor 20 through switches 12 and 13 through Winding 7 of relay 7 and by conductor 21 to line L". Relay 7 thereupon responds and establishes a maintaining circuit for itself extending from line L by conductors 20 and '22 through contact 7 by conductor 23 through switch 13 and thence through winding T to line L as already traced. In re sponding switch 7 establishes an energlzing circuit for relay 9 extending from line L ductor 27 through winding 9 by conductors 20, 22, 24 and 25 through contacts "1' and 8 of relays 7 and 8 by conof relay 9 and by conductors 28 and 21 to line L In responding relay 9 establishes an energizing circuit for starting switch 1 extending from line L through contact 7 of relay 7 as already traced by conductor 29 through relay 9 by conductor 30 through winding 1 of said starting switch and by conductors 31 and 32 to line L In responding switch 1 establishes low voltage power connections for stator A, the compensator windings 2 and 3 being then connected between lines L'L and L2L3 respectively, while the terminals T and T of stator A are connected to intermediate taps on compensator windings 2 and? respectively and terminal '1 of said stator is connected to line L The motor M then starts up as an induction motor, the field circuit thereof being connected in a closed loop through discharge resistance R by switch arm. 6 of field switch 6. Closure of switch 1 closes auxiliary switch 14 and an energizing circuit for relay 8 is then established extending from line L to and through contact 7 of relay 7 as already traced by conductor 33 through auxiliary switch 14 by conductor 34 through winding 8 of relay 8 and by conductor 21 to line I In responding relay 8 opens its contact 8 to interrupt the energizing circuit of relay 9 and in responding the same maintains itself by a circuit extending from line L through contact 7" of relay 7 as already traced by conductor 35 through contact 8 by conductor 34 through winding 8 to line L as already traced. Upon interruption of the energizing circuit of relay 9 the same opens subject to retardation by its dash pot and interrupts the energizing circuit of starting switch 1. Upon opening of starting switch auxiliary switch 15 closes to establish an energizing circuit for running switch 4 extending from line L through contact 7" as already traced through contact 8 by conductor 37 through auxiliary switch 15 by conductor 38 through winding 4" of running switch 4 and by conductors 39 and 21 to line L Running switch 4 thereupon responds to connect terminals T T and T of stator A to lines L, L and L respectively. Upon response of said running switch auxiliary contact 16 establishes an energizing circuit for field switch 6 extending from line L" through contacts 7", 8 and auxiliary switch 15 to conductor 38 as already traced by conductor 40 through auxiliary switch 16 by conductor 41 through winding 6 of field switch 6 and by conductors 42 and 21 to line if. Upon response of switch 6, the switch arms connect the field ll of motor M across the terminals or battery 38.

6 and 6* there- Upon establishment of the energizing circuit for running switch 4, relay 10 is energized by a circuit extending from line L through contacts 7", 8 and auxiliary switch 15 to conductor 38 as already traced by con-- ductor 43 through winding 10 of relay 10 and by conductors 44 and 21 to line L Relay 10 remains closed subject to de-energization thereof by relay 7 and assuming now that it is desired to stop the motor stop switch 13 is opened to interrupt the maintaining circuit of relay 7. Relay 7 then drops out and the contact 7 thereof interrupts the energizing circuits of running switch 4, field switch 6 and relays 8 and 10. Relay 10 is retarded in opening by its dash pot and prior to opening thereof contact 7 of relay 7 closes to establish an energizing circuit for plugging switch 5 extending from line l) by conductors 20, 22 and 24 through contact 7 by conductor 45 through relay 10 by conductor 46 through relay 11 by conductor 47 through winding 5 of said pl-, ugging switch and by conductor 32 to line L Plugging switch 5 thereupon responds and establishes a maintaining circuit for itself extending from line l1 to conductor 45 as already traced by conductor 48 through auxiliary switch 17 by conductor 46 through relay 11 and conductor 47 through winding 5 to line L as already traced. Closure of plugging switch 5 connects the stator A to lines L, L and L through compensator windings 2 and 3 but reverses the phase relation of the current supplied to the motor. The compensator windings 2 and 3 are then connected between lines LL and L 11 respectively while the outer terminals 'l and T of stator A are connected to the intermediate taps of windings 3 and 2 respectively and the middle terminal T of said stator is connected to line If. Prior to closure of plugging switch 5 field switch 6 has returned to normal position and the switch arm 6 thereof, connects the field F of the motor M in a closed loop extending through resistance R and winding 11 of relay 11. As is well-known, immediately upon establishment of the plugging connections the frequency of the current in the field circuit of the motor will be approximately twice that in the supply circuit T L and L and as the speed of the motor decreases the frequency of the current in the field circuit will decrease proportionately. When the motor is brought to rest the frequency of the current in the field circuit thereof will be the same as that in the supply circuit and relay 11 is calibrated to respond at such frequency but to remain unresponsive at higher frequencies. Thus relay 11 will open the energizing circuit of plugging switch 5 when the motor M is brought substantially to rest and upon opening of said switch the auxiliary switch 17 uis,

opens to insure against re-energization oil plugging switch by said relay.

.lt is desirable to interlock the switches It. 4% and 5 to insure against simultaneous closure tlnereoi and for this purpose interlocking means such as shown in Fig. 2 can he employed. The switches l, d and 5 are pro-v vided with downwardly extending tail pieces 5O. 5i and 52 respectively and as shown in Fig. en interlocking member 53 is arranged between tail pieces 50 and 5t while a similar interlocking member 5d is arranged. hetween toil pieces 5i end 52. Members 58 and are each provided with a loclring her 55 and each is pivoted to move in e plene nt suhstaitially right angles b0 the planes of movement of said toil pieces. Upon closure of any one of switches 1, 4 or 5 the toil piece thereof maintains the memhers 53 end 54: in positions wherein the hats 55 thereof loclr the other of suid switches in open position.

Referring to Fig. 3 the same illustrates a modification of the controller shown in Fig. l. A normally open voltage relay 60 is suhstituted tor the normally closed frequency responsive relay ll shown in Fig. l, The winding 50 or said relay is connected across the terminals o'l inductance coil 6i through a resistance lt andsaid coil is urranged for connection across the terminals oi field F by arm 8 oil field switch 6, As before set-forth upon establishment out plugging connections the frequency of the current in the field circuit oi? the motor will be approximately twice that in the supply circuit il -L and L and us the speed of the motor decreases the frequency oi' the current in the field circuit will decrease proportionetely, With the inductance coil 61 connected in the field circuit of the motor the voltage in said circuit will vary in the some ratio as the frequency. Due to the high ohmic resistance and relatively low inductance of the circuit through winding 60 relay 60 will respond to voltage variations hut will he practically independent of the frequeriey. Relay 60 and the resistance R are calibrated whereby said relay responds at a voltage corresponding to substantially a double frequency and to drop out at a volt age corresponding to. a frequency which is f the same as that in the supply circuit L, L and Lt. Thus the voltage relay performs the same function as the frequency re la 11 in Fig. l.

hat ll claim as new and desire to secure by Letters Patent is:

1. The combinatlon with a synchronous motor of control means therefor for selectively establishing power connections of a given phase relation for running andof a reversed phase relation for plugging and means associated with said former means whereby the same interrupts said p1uggingcontrol means to insure opening 0 connections under given electrical conditions in the field circuit of said motor.

2.. The combination with a synchronous motor of control means therefor tor selectively establishing power connections of a given phase relation for running and ot a reversed phase relation for plugging rand means associated with said former means necessitating establishment of said running connections prior to establishment oil said plugging connections and insuring interruption or said plugging connections under predetermined electrical conditions in the.

field circuit of said motor.

3. T he combination with asynchronous motor oft menus for establishing starting and running connections for said motor and means subjected to control by certain electrical conditions in the iield circuit of the motor for establishing plugging connections for said motor upon interruption of the running connections therefor.

The combination with a synchronous motor oil electro-responsive starting and running switches there-tor, an electro-responsive plugging switch for said motor, selective control means for said switches insuring closure of said plugging switch upon opening of said running switch and means subjected to control by certain electrical conditions in the field circuit of said motor to insure opening of said plugging switch when the motor is brought substantially to rest.

5. The combination with a synchronous motor of electro-responsive starting and running switches therefor, an electro-re sponsive plugging switch for said motor, selective control means for said switches insuring closure of said plugging switch upon opening of said running switch, said means including arelay responsive to certain electrical conditions in the field circuit ot said motor for insuring opening of said plugging switch when the motor is brought substantially to rest.

6. The combination with a synchronous motor of stator control means therefor ineluding electro-responsive switches for se-- lectively establishing power connections of a given phase, relation for running and of a reversed phase relation for plugging, field control means for said motor and selective control means for said switches insuring closure of said plugging switch upon opening of said running switch, said control means including a relay to be included in the field circuit of said motor by sai field plugging switch when the'motor is brought substantially to rest.

In witness whereof, I have hereunto subscribed my name.

. EDWIN 'W. SEEGER.

its

said i 

